The present invention belongs to a technical field of a glass substrate having formed thereon an oxide layer, which is used for automobiles, buildings, various industrial instruments, etc. Particularly, the invention belongs to a technical field of a glass substrate having formed an oxide layer on the necessary portions only of the surface thereof.
On the surface of a glass plate or a ceramic plate, oxide layers having various functions according to the use are formed. For example, as glasses used for automobiles, vehicles, buildings, etc., a heat-reflective layer containing the oxide of titanium, cobalt, etc., is generally used for the purpose of reducing the cooling load, etc. Also, as glass substrates for various displays, an electrically conductive film comprising tin oxide, etc., is used from the necessity of element driving. These layers are frequently formed on only parts of the surface of a substrate for the necessity of each use described above.
In not only the use of display but also other uses of automobiles, buildings, etc., there is a case of requiring that the layer is partially formed. For example, in the case of using a heat-reflective glass for the back window of automobile, it is required that a layer is not formed on the glass surface adjacent to a high-mount stop lamp disposed in the inside of the back window of the automobile but a layer is formed on other portion of the glass surface for shielding heat rays while ensuring visibility of the lamp.
In such a case, a method of foaming the layer after previously applying masking to the necessary portion of the glass plate or a method of applying masking after forming a layer on the whole glass plate and removing the remaining unmasked portion of layer with a solvent, by releasing, or polishing, etc., is employed.
However, according to the conventional methods as described above, masking is required in any method, which is accompanied by complicated steps and operations, and thus the effective and ensure partial formation of layer has been difficult by the conventional methods.
The present invention has been made to overcome the above-described problems.
Accordingly, an object of the present invention is to provide a method of partially forming a layer on a surface of a glass substrate by a simple and ensure method.
According to the present invention, the above-described object can be attained by the method of partially forming an oxide layer on a surface of a glass substrate, consisting essentially of:
(a) a step of forming a layer comprising an oxide on the surface of the glass substrate;
(b) a step of contacting a fixed portion of the oxide layer of step (a) with a paste comprising an inorganic compound, organic solvents, and silicon powder in order to dissolve the oxide layer of step (a) with the paste, wherein said inorganic compound is not the same as the oxide of step (a); and
(c) a step of removing the dissolved portion of the oxide layer from step (b) together with the paste.
The preferred embodiments of the present invention are as follows.
(1) The melting point of the inorganic compound is 500xc2x0 C. or lower or the softening point thereof is 500xc2x0 C. or lower.
(2) The dissolving step is a step of carrying out the dissolution by heating a fixed portion of the oxide layer together with the paste.
(3) The inorganic compound used in the paste includes at least one kind selected from the group consisting of phosphorus compounds each containing oxygen as a constituent and boron compounds each containing oxygen as a constituent.
(4) The phosphorus compound includes at least one kind selected from the group consisting of phosphoric acid and phosphates and the boron compound includes boric acid and borates.
(5) The inorganic compound is a glass and contains at least one kind selected from the group consisting of P2O5, PbO, B2O3, ZnO, and Bi2O3 as the constituent.